$ 0.64\% \div 5\% $
Convert each percentage into a decimal dividing by $100$ $ 0.0064 \div 0.05 $ ${0}$ ${0}$ ${5}$ ${6}$ ${4}$ ${0}$ $\text{Shift the decimal 2 to the right.}$ ${6}$ $\text{How many times does }5\text{ go into }{6}\text{?}$ ${1}$ ${5}$ ${1}$ $-\vphantom{0}$ ${6}\div5={1}\text{ or }5\times{1} = {5}$ ${4}$ $\text{How many times does }5\text{ go into }{14}\text{?}$ ${2}$ ${1}$ ${0}$ ${4}$ $-\vphantom{0}$ ${14}\div5={2}\text{ or }5\times{2} = {10}$ ${0}$ $\text{How many times does }5\text{ go into }{40}\text{?}$ ${8}$ ${4}$ ${0}$ ${0}$ $-\vphantom{0}$ ${40}\div5={8}\text{ or }5\times{8} = {40}$ $0.0064 \div 0.05 = 0.128$ Convert the decimal into a percentage by multiplying by $100$. $0.128 = 12.8\%$